To witness: last year at this time, EFCA had 47 Democratic co-sponsors out of 51 members in the Senate: the holdouts were Blanche Lincoln and Mark Pryor of Arkansas, Ben Nelson of Nebraska, and Ken Salazar of Colorado. This year, however, EFCA currently has only 40 co-sponsors, in spite of the fact that there are now 58 Democrats in the Senate.

Failing to renew their sponsorship are Max Baucus and Jon Tester of Montana, Evan Bayh of Indiana, Jeff Bingaman of New Mexico, Kent Conrad and Byron Dorgan of North Dakota, Dianne Feinstein of California, Herb Kohl of Wisconsin, Mary Landrieu of Louisiana, Claire McCaskill of Missouri, and Jim Webb of Virginia. Freshmen Senators Michael Bennet, Kay Hagan and Mark Udall and Mark Warner have also declined to sponsor the bill. Why does EFCA suddenly seem to have such a tough row to hoe?

One point of view is that its apparent support last year was ephemeral: Democrats knew that the bill was unlikely to get cloture, and that if it did somehow pass, it would become the subject of a Presidential veto. Therefore, they weren’t really committing themselves to much of anything. Common sense would dictate that when the stakes are low, it isn’t wise for a Democrat to thumb one’s nose at labor, which continues to play an instrumental and perhaps somewhat underrated role in getting Democrats elected. But now the stakes are high: EFCA really could pass, the business lobby knows it, and certain Senate Democrats are finding their support for labor to be something other than unequivocal.

The bill also suffers from poor timing: public support for unions tends to drop during recessions (although public support for corporations does too). Meanwhile, the White House is distracted, and will most likely be disinclined to spend significant time on the bill, much less its political capital. Labor, moreover, has had trouble beating back the “secret ballot” talking point, whereas conservatives came armed for the fight, and were making an active effort to undermine support for the bill since at least the failed auto bailout vote in December. Labor knows this (indeed, it never expected the battle over EFCA to be easy), and has been pushing back hard since roughly the time of the inauguration, but it let the secret ballot narrative get off to a running start and may now find it hard to catch up.

In spite of these obstacles, EFCA may still have some life in it. Firstly, the scenario that Reid envisions — a number of Senators vote for cloture on EFCA while voting against the underlying bill — is not entirely outside the realm of possibility. This is a vice of lobbying pressure between labor interests and business interests that a lot of conservative and moderate Democrats (and one or two moderate Republicans) don’t see a way out of: voting yes on cloture and no on the bill itself would be one way to split the baby. The other option, of course, is an amended bill that preserves the secret ballot while leaving the other protections for labor in place. Labor isn’t ready to go there yet — it’s not ready to give up on card check. But the Republicans have made so much of the secret ballot that if that provision were removed, they might find themselves somewhat disarmed.

Nate Silver is the founder and editor in chief of FiveThirtyEight. @natesilver538